Inkjet printers have printheads configured with a plurality of inkjets that eject liquid ink onto an image receiving member. The ink may be stored in reservoirs located within cartridges installed in the printer. Such ink may be aqueous, oil, solvent-based, or UV curable ink or an ink emulsion. Other inkjet printers receive ink in a solid form and then melt the solid ink to generate liquid ink for ejection onto the imaging member. In these solid ink printers, the solid ink may be in the form of pellets, ink sticks, granules, pastilles, or other shapes. The solid ink pellets or ink sticks are typically placed in an ink loader and delivered through a feed chute or channel to a melting device that melts the ink. The melted ink is then collected in a reservoir and supplied to one or more printheads through a conduit or the like. In other inkjet printers, ink may be supplied in a gel form. The gel is also heated to a predetermined temperature to alter the viscosity of the ink so the ink is suitable for ejection by a printhead.
Many inkjet printhead configurations include multiple inkjets that are formed in an array and are fluidly coupled to a single ink reservoir that supplies liquid ink to the inkjets. Each inkjet includes an actuator that ejects an ink drop from a pressure chamber in response to an electrical firing signal. During operation, multiple inkjets in a printhead often experience “cross-talk” where the operation of one inkjet is affected by the operations of other inkjets in the printhead during a printing operation. Sources of cross-talk include electrical cross-talk due to leakage of the electrical firing signal between the actuators for multiple inkjets, mechanical coupling between layers of the printhead that extend between multiple inkjets, such as a diaphragm layer that is coupled to the actuator in each inkjet, and fluidic pressure coupling that occurs when an inkjet ejects an ink drop and ink flows through shared ink conduits to refill the inkjet pressure chamber. As used herein, a reference to measuring or identifying “cross-talk” refers to measurement of variations in process direction placement of ink drops from inkjets in a printhead that are produced due to the effects of cross-talk. The measurement of cross-talk can be for individual inkjets or as an aggregate measurement for a printhead with multiple inkjets.
Excessive cross-talk in a printhead produces a significant change in the velocities of ink drops that are ejected from a given inkjet in the printhead during a printing operation compared to the velocity that drop would have if no other jets were firing. The effects of cross-talk are mostly perceptible near the edges of high-density printed images. For example, a solid printed line may appear to have an uneven edge because an alignment of the timing of the firing of the inkjets is typically performed in the absence of crosstalk. When a printhead experiences crosstalk, the process direction position of the drops change and thus produce the uneven edge. While numerous manufacturing and operating techniques that reduce printhead cross-talk are known to the art, some degree of cross-talk is often inherent to a printhead. The level of cross-talk between different printheads often varies due to variations in manufacturing of each printhead. Printheads with low levels of crosstalk would be desired for applications that require the highest quality printing. Consequently, improved methods for identifying levels of cross-talk in individual printheads to enable a printer to form high-quality images based on the cross-talk level for each printhead would be beneficial.